On commuting polynomial automorphisms of C k , k ≥ 3

We characterize the polynomial automorphisms of C 3 , which commute with a regular automorphism. We use their meromorphic extension to P 3 and consider their dyna- mics on the hyperplane at infinity. We conjecture the additional hypothesis under which the same characterization is true in all dimensions. We give a partial answer to a question of S. Smale that in our context can be formulated as follows: can any polynomial automorphism of C k be the uniform limit on compact sets of polynomial automorphisms with trivial centralizer